A touch screen recognizes user's screen touch or gesture as input information and is classified as a resistive type, a capacitance type, an ultrasonic wave type, or an infrared type according to an operating manner. Among such types, the capacitance type is a type in which when the touch screen is touched by a conductive object, a position of the object is sensed using a capacitance variation between the object and a transparent sensing electrode. A capacitance type touch screen has the following good characteristics as compared with other types of touch screens: long life, thin thickness, and fast response. For this reason, the capacitance type touch screen is used in various fields.
As a screen of an electronic device becomes larger and the size of the electronic device is scaled down, recently, a touch screen coupled with a display is used as a unique input means without an input device such as a keypad.
The extended application of such a touch sensing device accompanies a variation in an input manner: a manner for sensing two or more multi-touch inputs. To recognize two or more touch inputs at the same time, it is necessary to sense relative motions of two or more touch inputs or to sense absolute coordinates of two or more touch inputs independently. In recent years, a lot of manufacturers have used a touch screen to which a drive-sensing principle for computing absolute coordinates of multi-touch inputs is applied to overcome a ghost phenomenon.
In case of the multi-touch input, in general, there is no problem to recognize a multi-touch input about plural points that are spaced apart from each other on a screen. However, when a plurality of touch inputs occurs at adjacent points, regions where touch inputs occur are partially overlapped. On this occasion, there is a problem to recognize the touch inputs as independent touch inputs, respectively. Also, when a touch input having a wide area occurs, it is not recognized as one touch input, but it is erroneously recognized as a plurality of touch inputs. Thus, there is required a multi-touch input processing method for computing an input point exactly when touch inputs simultaneously occur at a plurality of points adjacent to each other.